Development of a Biomimetic Metallic Femoral Stem: Methodological Approach

Abstract

In this communication, a new methodological approach is proposed to develop a biomimetic metallic femoral stem. The design of this stem starts with the definition of an outer skin by reproducing the shape and overall dimensions of a Stryker® femoral stem to be implanted in an artificial femur model from Sawbones®. In-house algorithms are then used to generate two types of porous structures inside the outer skin: either a stochastic cubic-based porous structure or an ordered diamond-type porous structure. Next, a model of the femur-stem assembly is developed using the finite element method. The fully dense Stryker stem replica and two porous stems are fabricated using selective laser melting technology. Then, comparative mechanical testing is carried out using the ISO 7206-4 (2010) guidelines. These tests are conducted on an intact artificial femur (reference case) and on the identical femurs, but now implanted with the fully dense and porous stems. Using digital image correlation tools, the results of four series of tests are compared to assess which implant design leads to the lowest stress shielding in the implanted femur. Finally, the experimentally measured strain fields are compared to the numerical predictions to validate the numerical models.